Psotkactob



Sept. 2, 1924. v 1,507,027

' J. D. M LEOD PROTRACTOR Filed June 5, 1922 'IIIIIIIIIII Inventor Jbhm/ JLM L e 0 d 5 wttorncy Patented Sept. 2, 1924.

UNITEDQSTVATETS Jenn 11' Morison, or oAKMonT, PENNSYLVANIA.

PRo'rnAo'roR.

Application filed June 3,

To all whom it may concern a Be it known that 1, JOHN D. MoLnoD, a citizen of the UnitedStates,residing at Oakmont, in the county of Allegheny and State of Pennsylvania, haveinvented certain new and useful Improvements in a Protractor, of which the following is a specification.

My invention relates to improvements in a protractor particularlyadapted for use by architects and engineers for making drawings, and for other work requiring great accuracy, and which will be of assistance in solving trigonometrical problems.

The object of my invention is to construct protractor comprising a semicircularplate or base graduated to indicate degrees of an are, a disk concentrically mounted upon the base and rotatable independently of the base,

and an arm, adapted to lee-adjusted to various radial positions upon the disk. A still further object of my invention is to provide a cylinder which is movablerelatively with the disk and having reading marks thereon by which the movement of the disk and arm= may be indicated, and showing the relation between said parts and the semicircular portionofthe base; andia still further. object of my invention is to provide various novel features of construction and arrangement of the parts, which will be more fully herein after described and claimed. I, v

Referring to the accompanying drawing, F 1,is a plan view of my improved protractor; Fig. 2. is a side elevation of the pro tractor, as shown in Fig. 1 Fig. 3, is an end elevation of the protractor as shown. in Fig. 1, and" Fig. -11 is avertical sectional view on line 44Fig.. 1. A

In the drawings, in which like reference characters refer to like parts, 1 represents a base consisting of a semicircular portion'2', having graduations arranged thereon ad a; cent to 1ts edge indicating degrees of a circle.

Said base having a portion forming a bearing plate 3, of less width than the portion 2,; thus forming shoulders 4 and 5 on the portion 2 arranged in alignment with the center of the semicircular portion 2 which facilitate the placing of the protractor-upon.

a given line-upon a drawing.

The base 1, is vprovided wi block 7, positioned concentrically with, the semicircular part2. Saidbearing block 7- is provided witha facing surface 8, upon which is mounted a;disk 10, in a plane slightly ele-- vated above {thebase 1;-- A pivot pin 12 is a asing 1922. Serial No. 565,636.

secured in, the centerof the bearing block 7- uponwhich-the disk 10 is rotatable.

1. An arm 13 is adjustably secured upon the disk 10 by said pivot-pin 12 and by a-fasten' ingdevice consistingof a bolt 15 slidably.

mounted in a semi-circular slot 18 formed'in' the disk and by a thumb nut 16 upon the bolt 15 for clamping the arm 13 upon the upper surface of the disk 10.. The arm 13 is provided with an off-set portion 19, whereby the blade20,forming partof the arm 13, willextend immediately above the semicircular portion 2 of the base, so that the side edge of and 24. formed therein adapted to receive the pivot pin 12. Said notches are vpositioned, in

alignment with thelongitudinal side edges of the blade portion 20 of thearm 13, so that. 1 1

either edge ofthe blade:2 0 maybe used for reading the graduation upon the base. By

loosening the thumb nut 25, upon the pivot, pin 12 and thethumbnutlG 'on the bolt: 15,

thearm 13 maybe'shifted so that either of the notches 23, or 21 will-embracefthe' pivot,

pin. 12 The arm 13 is'provided with a slot 27 which permits the arm to slide 'upon the bolt 15 sufficient-ly .torelease the:hcad.-22"v from thepivotrpin 12 the arm can then be turned on the bolt 15 as a pivot to bring theopposite notch into alignment with the pivot pin .12, which will position theopposite edge i of the blade portion .20, of the ,arnninradialf alignment with. the pivot 1311112., By means: .ofi -the bolt 15 and thumb nut. 16 the arm 13 may be set atany radial position throughout the length of .theslot 18 formed in the disk 10, The thumb nut 25 is not clamped tightly. upon the head 22 of the arm, as itis intended that, the pivot pin 12 remainrstationary and the arm and disk are allowedto-rotate freely- I v f tating .the' disk for upon the pivot pin 12,

The vmechanism for r turning the arm over the fgraduations; upon the base, conslsts of a shaft-.30,-rotat ably .mountedin bearings 31 and 32,, secured to the bearing plate 3-forming partofthe. base-1 The shaft 30 is providedfwithl al worm v3 1 which mesheswith the teeth 35' formed upon theperiphery of the disk 10;

Upononerendof theshaftsecured a; gear-wheel 36. which meshes with a ;g ar,-, wheel 37 secured .to a shaft 40, jrotatably mountedin the -.beari ngs Bland 32, and hav; I

the; pivotpin whereby either edge of the arm may be placed upon a radial line, and a fastening device located adjacent to the periphery of thedisk for holding the arm in various radial positions upon the disk.

6. A protractor 'comprising'a base, a semicircular portion upon the base having graduations thereon, a bearing block mounted upon the base and having an elevated facing surface formed thereon, a disk mounted upon the facing surface of the bearing block, said disk having a semicircular slot formed therein located adjacent to one edge thereof, an arm mounted upon the disk having its inner end pivoted concentrically with the semicircular portion of the base and a clamping device slidably mounted upon the disk throughout the length of said slot adapted for holding the arm in different radial positions upon the disk.

7. A protractor, comprising a base, a semi circular portion on the base graduated to indicate fractions of a circle, a bearing block upon the base having a facing surface extendingin a plane parallel with the base, a disk rotatably mounted upon the bearing block positioned concentrically in relation to the said semicircularportion of the base, an arm mounted upon. the disk and extending radially therefrom, a cylinder having graduations thereon mounted upon the base, and mechanism interposed between the cylinder and the disk for rotating the cylinder and the disk.

8. A protractor comprising a base, a semicircular portion uponthe base having graduations thereon, a bearing block mounted upon the base and having an elevated facing surface formed thereon, a disk mounted upon the facing surface of the bearing block, mechanism upon the base for rotating the disk, an arm mounted upon the disk extending radially therefrom, and said arm havingan offset portion formed therein whereby the free end of the arm will be positioned adjacent to the surface of the base carrying said graduations.

9. A protractor comprising a base, a semicircular portion on the base graduated to indicate fractions of a circle, a pivot pin centrally mounted upon the base, a disk rotatably mounted upon the pin, an arm adjustably mounted upon the disk, bearings upon the base, a shaft rotatably mounted in the bearings for rotating the disk, a cylinder mounted upon the bearings, mechanism for rotating the cylinder and the shaft simultaneously, a bar extending lengthwise of the cylinder, posts at either end of the bar for holding the latter in a fixed position, reading marks upon the bar, and graduations upon the cylinder indicating fractions of the graduations upon the semicircular portion of the base when read upon the bar.

10. A protractor comprising a base, a

semicircular portion ,on the base graduated toindicate fractionsof a circle, a pivot pin centrally. mounted upon -the ,base, a disk rotatably mounted upon the 'pin,; an arm adjustably mountedupon the disk, shaft rotatably mounted uponthe base, aworm upon thepshaft, teeth. formed upon :the

periphery of the disk in engagement with the worm, a cylinder mounted upon the base, graduations upon the cylinder, gear wheels for communicating motion from the shaft to the cylinder, and a member 'mounted upon the base and associated with the cylinder for reading the graduations on the cylinder indicating fractions of the graduations on said semicircular portion of the base.

11. A protractor comprising a base, a

semicircular portion on the base graduated to indicate fractions of a circle, a pivot pin centrally mounted upon the base, a disk rotatably mounted upon the pin, an arm adjustably mounted upon the disk, a shaft rotatably mounted upon the base in operative engagement with the disk for rotating the latter, a cylinder mounted upon the base and in rotatable engagement with the shaft, said cylinder having graduations arranged thereon-proportional to the graduations upon the semicircular portion of the base and a member mounted upon the base and associated with the cylinder for read ing the graduations on the cylinder.

12. A protractor comprising a base, a semicircular portion on the base graduated to indicate fractions of a circle, a pivot pin centrally mounted upon the base, a disk rotatably mounted upon the. pin, an arm adustably mounted upon the disk, gear-teeth formed upon the periphery of the disk, a.

shaft mounted upon the base, a worm upon the shaft meshing with the teeth upon-the disk, a cylinder mounted upon the base, gear wheels interposed between the cylinder and the shaft whereby one revolution of the cylinder will move the arm over one of the said graduations formed upon the base, said cylinder having graduations arranged thereon, and a bar mounted upon the base and associated with the cylinder forreading the graduations on the cylinder.

13. A protractor comprising a base, a

a'ba'r mounted in a fixed position in relation to the surface of the cylinder, said cylinder having graduatio-ns arranged thereon dividing its periphery into equal parts, saidcylinder having graduations arranged thereon dividing its length into equal parts, said bar having reading marks thereon cortioned obliquely in relation to the gradua- 10 tions extending lengthwise of the cylinder.

In testimony whereof I affix my signature.

JOHN D. MoLEOD. 

